Through years of perfecting their techniques, a team led by Bursac and graduate student Mark Juhas discovered that preparing better muscle requires two things—well-developed contractile muscle fibres and a pool of muscle stem cells, known as satellite cells.

Every muscle has satellite cells on reserve, ready to activate upon injury and begin the regeneration process. The key to the team's success was successfully creating the microenvironments—called niches—where these stem cells await their call to duty.

Having developed such engineered muscle, they needed to test it out. In the lab, they damaged it with a toxin found in snake venom—and saw that the satellite cells multiplied and successfully healed the injured muscle fibres. That's pretty badass.

Then, they inserted the muscle into a small chamber placed on the backs of live mice and watched, through a tiny glass window, to see what happened. It could grow and repair in just the way they expected given their previous success.

So, they now have engineered muscle that, for the first time, can heal itself inside living tissue. The next step, say the researchers, is to see if the muscle can be used to repair actual muscle injuries and disease. [PNAS via Duke]